Hyeong Choi

2-(2,5-Dimeth­oxy­phen­yl)-N-[2-(4-hy­droxy­phen­yl)eth­yl]acetamide

In the title compound, C18H21NO4, the dihedral angles between the acetamide group and the methoxy- and hydroxy-substitured benzene rings are 80.81 (5) and 8.19 (12)°, respectively. The benzene rings are twisted with respect to each other, making a dihedral angle of 72.89 (5)°. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

N-(4-Hy­droxy­phen­yl)-3,4,5-trimeth­oxy­benzamide

In the title amide compound, C16H17NO5, the dihedral angle between the benzene rings is 71.59 (4)°. In the crystal, intermolecular N—H⋯O and O—H⋯O hydrogen bonds link the molecules into a two-dimensional array parallel to the ab plane.

1-(4-Hy-droxy-phen-yl)-3-(3,4,5-tri-methoxy-phen-yl)thio-urea.

In the title compound, C16H18N2O4S, the dihedral angle between the hydroxyphenyl ring and the plane of the thiourea moiety is 54.53 (8)°. The H atoms of the NH groups of thiourea are positioned anti to each other. In the crystal, intermolecular N—H⋯S, N—H⋯O, and O—H⋯S hydrogen bonds link the molecules into a three-dimensional network.

N-(3,4-Difluoro-phen-yl)-3,4,5-trimethoxy-benzamide.

In the title amide, C16H15F2NO4, the dihedral angle between the benzene rings is 2.33 (15)°. Molecules are linked in the crystal structure by N—H⋯O hydrogen bonding involving N—H and C=O groups of the amide function, leading to a supramolecular chain along [100].

Electric Heating Performance of Pyrolyzed Photoresist Films Prepared by Proton Irradiation and Pyrolysis

In this study, pyrolyzed photoresist films (PPFs) were prepared using commercial SU8 photoresist by proton irradiation and pyrolysis. SU8 thin films were irradiated with high-energy proton ions and then pyrolyzed in a tube furnace at 1000 °C under inert atmosphere. The carbonization yield of the PPFs increased with an increasing fluence due to the formation of more crosslinked network structures at a higher fluence. The electrical resistance decreased with an increasing fluence due to the higher remaining thickness and carbonization yield at a higher fluence. Therefore, the PPFs prepared at 1 × 1016 ions/cm2 showed the maximum temperature of 150 °C at 20 V and a high electric power efficiency of 1.57 mW/°C.

Thermal Insulation Performance of Cotton and PET-based Hybrid Fabrics Impregnated with Silica Aerogel via a Facile Dip-dry Process

We report the morphological features and thermal insulation properties of a series of cotton- and PET-based hybrid fabrics impregnated with silica aerogel. For the purpose, commercially available cotton and PET knitted fabrics were dipped into aqueous dispersions including different silica aerogel contents, dried, and stacked to 1, 3, and 5 layers. The SEM images revealed that the silica aerogel particles were well incorporated into cotton or PET knitted fabrics. The thermal insulating performance of the hybrid fabrics as functions of the silica aerogel content and the number of layers of stacked fabrics were characterized by monitoring the surface temperatures of the fabrics on a plate with a wide temperature range of ~50-80 oC using an infrared camera. The higher thermal insulation performance was attained for both cotton- and PET-based hybrid fabrics with higher silica aerogel contents. In addition, 3-layered hybrid fabrics exhibited noticeably improved thermal insulation performance, compared to 1- or 5-layered fabrics. The thermal insulation property of the cotton-based hybrid fabrics was dominantly influenced by silica aerogel than that of PET-based hybrid fabrics. The overall results demonstrated that the cotton- and PET-based hybrid fabrics with silica aerogel manufactured by a facile dip-dry process could be utilized as protective garments, heat-sensitive devices, pipes, automotive, aircrafts, and buildings for thermal insulation applications.

1-(3-Hy-droxy-phen-yl)-3-(3-meth-oxy-phenyl)thio-urea.

In the title compound, C14H14N2O2S, the dihedral angles between the thiourea group and the methoxyphenyl and hydroxyphenyl rings are 61.91 (4) and 76.90 (4)°, respectively. The benzene rings are twisted with respect to each other, making a dihedral angle of 71.03 (4)°. The H atoms of the thiourea NH groups are positioned anti to each other. In the crystal, intermolecular N—H⋯S, N—H⋯O and O—H⋯S hydrogen bonds link the molecules into a three-dimensional network.

1-(2-Hy-droxy-2-phenyl-eth-yl)-3-(4-meth-oxy-phen-yl)urea.

In the title compound, C16H18N2O3, the dihedral angle between the 4-methoxyphenyl ring and the urea group is 35.6 (2) °. The H atoms of the urea NH groups are positioned syn to each other. In the crystal, intermolecular N—H⋯O and O—H⋯O hydrogen bonds link the molecules into a two-dimensional array in the ac plane; the carbonyl-O atom is trifurcated.

1-[3-(Hy­droxy­meth­yl)phen­yl]-3-phenyl­urea

In the title compound, C14H14N2O2, the dihedral angle between the benzene rings is 23.6 (1)°. The H atoms of the urea NH groups are positioned syn to each other. In the crystal, intermolecular N—H⋯O and O—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

N-(2,5-Dimeth­oxy­phen­yl)-N′-[4-(2-hy­droxy­eth­yl)phen­yl]urea

In the title compound, C17H20N2O4, the 2,5-dimethoxyphenyl unit is essentially planar, with an r.m.s. deviation of 0.015 Å. The dihedral angle between the benzene rings is 43.66 (4)°. The molecular structure is stabilized by a short intramolecular N—H⋯O hydrogen bond. In the crystal, intermolecular N—H⋯O and O—H⋯O hydrogen bonds link the molecules into a three-dimensional network.